1. I know there are some kind of tools that can do this job for you, but it's not 100% guranteed. And, it's no need for you to do this if your computer works fine. Only a tip: To keep your computer in sharp, be sure that the disk with OS on it has at least 100M free space.
2. You can change the username of office. Just go to Tools-->Options and select the "User Information" tab.